\begin{tikzpicture}
    \tkzDefPoints{0/0/O}
    \tkzDefPoint(120:1.5){A}
    \tkzDefPoint(225:1.5){B}
    \tkzDefPoint(315:1.5){C}
    \tkzDefPointOnLine[pos=1.4](B,A)  \tkzGetPoint{E}
    \tkzDefLine[bisector](C,A,E)  \tkzGetPoint{d}
    \tkzInterLC[common=A](A,d)(O,A)  \tkzGetFirstPoint{D}

    \tkzDrawCircle[thick](O,A)
    \tkzDrawPolygon(A,B,C)
    \tkzDrawSegments(A,C  A,D  A,E  B,D  C,D)
    \tkzLabelPoints[left, yshift=.5em](A)
    \tkzLabelPoints[left](B)
    \tkzLabelPoints[right](C)
    \tkzLabelPoints[above](D)
    \tkzLabelPoints[left](E)
\end{tikzpicture}

